Winter Haven, Florida -- Polk County Sheriff's detectives have cracked a murder case that went cold for two decades.

In June 1993, the body of 39-year-old Jahala Watson was discovered on the side of a rural road in Sumter County by a truck driver. Her car was found abandoned at a Walmart store in Lakeland.

Detectives say she died after being stabbed in the neck. She was 7 1/2 months pregnant with a boy she had named Skylar.

Sheriff Grady Judd says all of the evidence they've gathered over the years points to her son, now 39-year-old Christopher Shane Knight (Watson). He changed his last name to Knight after his mother's death, which is her maiden name.

"All of our circumstantial evidence, every bit of it, all of our witnesses, every one of them clearly indicate to us that no one had the opportunity to murder her and he was th one that not only had the opportunity, not only had the motive, but was the one who went out of his way not to report her missing," said Sheriff Judd.

Detectives say Knight, who took on his mother's maiden name in the years after his death, would fight viciously with his mother who he still lived with.

The two were fighting on the last day she was seen alive.

Sheriff Judd says Knight told his friend to leave the house during the fight, "Four to five minutes later, everything was silent. Jahala Watson is never heard from or seen from that moment. There's only one person in the house with Jahala Watson and that's her son."

Sheriff Judd says Knight walked out of the house ten minutes later freshly showered and wearing new clothes before leaving the house with friends.

His mother's body was discovered three days later.

Detectives say Knight has cooperated with them over the years and always came in to be interviewed. But, it was what he's told them over the years that eventually built a circumstantial case against him.

According to the arrest affidavit, in 1995 Knight was asked if he killed his mother. The report states, "Shane stated, "I want to say no, but I might have.' Shane stated, "it all points to me' and that 'it looks to me like I done it'. He said looking at all the evidence...he would put himself in the electric chair."

In 2001, he made another statement according to the same affidavit. "I made peace with the Lord" when referring to what happened to Jahala.

The various incriminating statements and changes of stories compiled together was enough for detectives to put what they call an "iron clad" circumstantial case against him.